Sometimes science is fortunate, as was physics in the measurement of temperature: it just so happened that the change in volume of a quantity of mercury, by which the first temperature measurements were made, occurred according to simple laws of physics, and was independent of changes in many other conditions (air pressure, amount of mercury, rate of heat transfer, etc.), varying only with changes in an important property of a substance, its temperature. Whether social science can be so fortunate remains to be seen.

But in the meantime, we take our vague and fragmentary theories, about attitudes being the determinants of behavior, about norms being social prescriptions for behavior, and on the basis of these vague and often implicit theories we construct measurements of these hypothesized underlying properties, using manifest observations of one sort or another. Sometimes such construction is highly rationalized, with mathematical operations made upon the data in order to construct the underlying property.